The present invention relates to telephone network interface devices. More particularly, the invention relates to a telephone network interface organization containing comprehensive modifications directed to improvements in the design, fabrication and utilization of such equipment.
Telephone network interface equipment has utility in an environment in which telephone service is delivered to a plurality of subscribers and has as its purpose to isolate the telephone company ("telco" herein) portion of the system or wiring from that serving the respective subscribers. Such isolation is desirable in order to segregate the responsibility for faults or malfunctions that may occur in the respective parts of the system.
In practice such equipment normally comprises a container or housing, the interior of which is divided into a "telco" portion and a subscriber portion. Covers are provided for the respective housing portions that permit only telco access to the telco portion of the housing and both telco and subscriber access to the subscriber portion thereof. In such housings of the prior art the covers are pivotally mounted to the housing by means of pin-type hinges which suffer the disadvantage that separate hinge assemblies are required for mounting to both the housing and the cover or panels therein; the requirement for a pin introduces an extraneous part to the connection; and the need to carefully align the hinge elements in order to install the pin renders removal and replacement of the covers both laborious and time consuming. It is the amelioration of these problems, therefore, that is addressed by one aspect of the invention.
Moreover, the subscriber portion of the housing normally contains a plurality of individual subscriber terminal units (commonly referred to as "terminal strips") which support the terminals for subscriber wiring and are disposed in adjacently stacked array along the base of the housing. Such devices are separate units that are removably and interchangeably installed in the housing typically on an individual module containing a network interface jack. Separable terminal strips employed in prior art network interface devices are of two principal types. The first, of which the device disclosed in U.S. Pat. No. 4,741,032, issued Apr. 26, 1988 to Hampton is representative, requires use of a tool such as a screw-driver for its removal. This form of terminal strip is undesirable in that the need for a tool for its attachment and removal is an inconvenience. More importantly, however, is the fact that, since the attachment screw for the device is clearly visible and accessible, unauthorized use of telephone service can occur by a subscriber's removal of the terminal strip from its assigned position and placement at an adjacent interface jack whereupon service can be misappropriated through the line of another subscriber. The second form of terminal strip is one such as that described in U.S. Pat. No. 4,979,209, issued Dec. 18, 1990 to Collins et al., in which no positive fastening means is employed to secure the terminal strip to the housing whereby removal from the assigned service line may occur not only intentionally but accidentally, as well. Consequently, according to another aspect of the disclosed invention there is provided for use with the terminal strip, a latching mechanism that is not apparent to one untrained with the equipment, yet effective to positively secure the strip against removal.
Terminal strips contemplated for use in the disclosed network interface arrangement are, furthermore, provided with an improved security cover arrangement. Multi-line network interface devices, as typified in U.S. Pat. Nos. 4,749,359, 4,825,466, 4,979,209 and 5,153,910, are normally provided with individually lockable security covers over each termination in order to prevent unauthorized access thereto. Such covers also serve to protect against inadvertent electrical shock; to provide a place for identifying markings; and to align and secure the interface plug and associated sealing members. The covers, as shown in these prior patents, may be pivotally hinged either to the body of the interface jack or to the housing which mounts the jack. A major disadvantage with such arrangements is that, since responsibility for the cover, plug and terminal strip rests with the subscriber, if for any reason the telephone company must replace the jack or housing, it must of necessity replace the cover thereby destroying or eliminating any identifying markings carried thereby. This problem is avoided by practice of the present invention wherein the security cover is hingedly attached, instead, to the terminal strip body which is, itself, removable from the jack thereby facilitating movement of subscriber terminal strips with wiring and cover intact for line reassignment from one network interface jack to another. Thus, not only is it unnecessary to unwire and delicately remove the terminal strip from the housing, but also any markings present on the cover are preserved.
According to another aspect of the invention improvements are made in the means for grounding the separate interface modules in the network interface system wherein it is known to ground each terminating device. U.S. Pat. Nos. 4,882,647 and 4,979,209, both to Collins et al., describe means for grounding in the form of a ground bus specially adapted to mount and connect a plurality of protecting elements. While the grounding means described in these patents constitute improvements over a grounding system in which separate wires extend from one protecting element to the other, they are not totally dispositive of all problems that are manifest in the concerned systems. For example, the ground bus device embodied in the disclosed apparatus comprises a plurality of individual ground bar sections or modules that can be fabricated as uniform members and a prescribed number of which can be installed in a container or housing dependent upon the number of protecting elements to be accommodated therein.
The ground bus devices may also be advantageously provided with tangs on which the protected terminating devices are mounted, each such tang bearing a detent in the form of a depression or hole for reception of a specially configured spring-biased projection on the electrical contact or "ground clip" that seats in the detent. Such detents provide a positive indication that the devices are properly seated, as well as a supplemental retention force against removal of the device.
Further according to the disclosed invention, the housing which defines the containment for the network interface system possesses a physical layout that is especially designed to facilitate movement of the respective subscriber terminal strips for line reassignment from one interface jack to another without need for unwiring and rewiring the affected members of the system.